This invention relates to a leveling system for use with a vehicle, such as a recreational vehicle.
Various systems for leveling a recreational vehicle are known, such as are shown in U.S. Pat. Nos. 4,061,309; 4,165,861; 4,597,584; 4,743,037; and 4,746,133. These patents all show a leveling system having four jacks located one adjacent each corner of the vehicle.
It is an object of the present invention to provide a three-leg system for leveling a vehicle. It is a another object of the invention to provide a leveling system which is simple and efficient in its construction, and which is easily operated and provides highly satisfactory performance. It is a further object of the invention to provide a vehicle leveling system which is efficiently packaged and provides a minimal number of hydraulic and electrical connections to install. It is a further object of the invention to provide a leveling system which is adaptable for installation on a wide variety of vehicles.
In accordance with the invention, a system for leveling a vehicle, such as a recreational vehicle, comprises a number of extendable and retractable fluid-operated jacks mounted to the frame of the vehicle. In a preferred form, the system includes three jacks, two of which are located at opposite sides of the rear of the vehicle frame, with the third jack being centrally located at the front end of the vehicle frame. The system further includes a selectively operable source of pressurized fluid, such as a hydraulic pump, for supplying pressurized fluid from a reservoir. Broadly, the system includes a leveling arrangement for selectively providing pressurized fluid to certain of the jacks, to extend the jacks and to level the vehicle. Each jack includes a spring urging it to retract, with fluid pressure supplied to the jack overcoming the force of the spring to cause extension of the jack. When it is desired to retract the jacks, the leveling arrangement opens the jacks to reservoir to allow the springs to retract the jacks and to expel fluid therefrom to the reservoir.
The invention provides a number of features which provide highly advantageous construction, operation and/or installation of the vehicle leveling system.
In accordance with one feature of the invention, fluid pressure from the pump is provided to a primary supply/return line. A series of secondary supply/return lines each extend between the primary supply/return line and one of the jacks. A supply/return control valve is disposed in each secondary supply/return line. Each supply/return control valve is movable between a first position providing communication between the primary supply/return line and one of the jacks, to provide supply or return flow of fluid through the secondary supply/return line and the supply/return control valve, and a second position cutting off communication between the primary supply/return line and the jack. A return line communicates between the primary supply/return line and the reservoir, and a return control valve is disposed in the return line. The return control valve is movable between a first position allowing return flow from the primary supply/return line to the reservoir, and a second position preventing return flow to the reservoir through the return line. This feature of the invention minimizes the number of valves required to provide extension and retraction of the legs, thus reducing the cost of the system and entailing less wiring to install the system. Vehicle leveling systems of which the applicants are aware employ a number of valves equally twice the number of jacks, to provide extension and retraction of the jacks. That is, known four-jack systems require eight valves, whereas known three-jack systems require six valves. In accordance with this aspect of the invention, a three-jack system requires four valves to extend and retract the jacks, whereas a four-jack system requires five valves.
In accordance with another feature of the invention, a bidirectional flow-control valve is located between each jack and the primary supply/return line, to provide slow retraction of the jacks until the vehicle wheels engage the ground, and to thereafter provide fast retraction of the jacks once the load on the jacks has been relieved by the vehicle wheels. This feature of the invention reduces the overall time required to retract the jacks.
In accordance with another feature of the invention, a low pressure switch is interconnected with the primary supply/return line for detecting a threshold pressure which indicates that all of the jacks have engaged the ground, and for thereafter commencing operation of the leveling arrangement to level the vehicle. In a preferred form, the primary supply/return line is a passage formed in a manifold, and the low pressure switch is mounted to the manifold so as to be in communication with the primary supply/return line passage to detect the low pressure threshold within the primary supply/return line passage. In addition, a high pressure switch is preferably mounted to the manifold so as to be in communication with the primary supply/return line passage. The high pressure switch is interconnected with the leveling arrangement to terminate its operation when a high pressure threshold is attained, such as occurs when one of the jacks is fully extended. Mounting of the low and high pressure switches directly to the manifold provides advantageous packaging of the manifold, valve and switch components.
In accordance with yet another feature of the invention, the reservoir comprises a tank, and the pump is located within the tank. A motor drives the pump, and the pump and motor are mounted to the tank through a mounting arrangement which includes a supply passage forming a portion of the supply line for providing supply of flow of fluid from the tank in response to operation of the pump, and a return passage forming a portion of the return line for providing return flow of fluid to the tank. The manifold, in which the primary supply/return line passage is formed, is adapted for direct mounting to the pump and motor mounting arrangement for establishing direct communication between the supply and return passages formed in the mounting arrangement and a supply and return passage, respectively, formed in the manifold, each of which is in communication with the primary supply/return line passage. The direct mounting of the valve manifold to the pump mounting arrangement eliminates the need for connecting hydraulic hoses between the valve manifold and the reservoir, and provides a clean assembly which can easily be installed on the vehicle frame.
In accordance with yet another feature of the invention, the tank includes an end wall and one or more side walls, which cooperate to form a corner. An intake tube extends from the pump into the tank for providing intake of fluid to the pump from an inlet, and a discharge tube extends from the pump into the tank for discharging fluid into the tank from an outlet. The intake tube inlet and the discharge tube outlet are located in close proximity to each other, and also in close proximity to the corner. With this arrangement, the tank can be mounted such that either the end wall or the side wall adjacent the corner defines the lowermost extent of the tank. This feature accommodates mounting of the tank to the vehicle frame such that a longitudinal axis of the tank is oriented either horizontally or vertically.
In accordance with another feature of the invention, the vehicle has a suspension which includes one or more inflatable and deflatable air bags and a source of pressurized air, and the invention includes a pneumatic control system for inflating and deflating the airbags. The vehicle suspension includes one or more air pressure supply valves interposed between the source of pressurized air and the air bags. Each supply valve is movable between a first position for supplying pressurized air to the air bags, and a second position for cutting off supply of pressurized air to the air bags. The pneumatic control system of the invention includes one or more relay valves located between each supply valve and the air bags. Each relay valve is movable between a first position establishing communication between a supply valve and one or more air bags, and a second position for exhausting air from one or more air bags. A control valve is provided for selectively moving the relay valves between their first and second positions. The control valve is interconnected with the leveling arrangement for moving the relay valves to their second position to exhaust the air bags prior to leveling of the vehicle, and for moving the relay valves to their first position to fill the air bags after retraction of the legs and prior to operation of the vehicle. The control valve is preferably an electrically operated valve disposed between the pressurized air source and each relay valve. The relay valves are movable between their first and second positions in response to supply of pressurized air, and the control valve is movable in response to the leveling arrangement between a first position for supplying pressurized air to each relay valve from the pressurized air source, and a second position for cutting off supply of pressurized air to the relay valves. This feature of the invention provides a single solenoid-operated control valve which selectively supplies air pressure to the relay valves, thus minimizing the electrical wiring involved in installing the pneumatic control system. In addition, the control valve maintains pressure within the pressurized air source, such as a pressurized air tank, even during and after exhaustion of the air bags.
In accordance with a further feature of the invention, each supply/return control valve is manually movable from its second position to its first position, as is the return control valve. This feature allows the operator to position the supply/return control valves and the return control valve so as to allow the jacks to retract due to operation of the spring associated with each jack, in the event of an electrical failure of the system. In addition, pneumatic control valve is manually operable so as to allow the air bags to be filled in the event of an electrical failure of the system.
In accordance with yet another feature of the invention, the leveling arrangement is interconnected with the transmission neutral switch and the parking brake switch. When the operator starts the vehicle engine while the jacks are extended and either the parking brake is disengaged or the transmission is taken out of neutral or park, the jacks are automatically retracted.
In accordance with a further feature of the invention, the front jacks are retracted before the rear jacks when the operator initiates retraction. This minimizes side loads which can be incurred due to the geometry of the vehicle suspension during lowering of the jacks. The front jacks are preferably retracted until the front wheels engage the ground and the front jack is lifted from the ground, before the rear jacks begin retraction.
In accordance with a further feature of the invention, the leveling arrangement is interconnected with a sensing system for sensing voltage across the pump motor, which is operated off the vehicle battery. In the event the vehicle battery voltage is low/ the current supplied to the pump from the battery will increase, and may cause damage to the pump. The sensing system senses if the voltage at the pump falls below a predetermined threshold, and operation of the leveling arrangement is terminated if the voltage at the pump motor is less than the predetermined threshold. When this occurs, the jacks can still be retracted to allow operation of the vehicle.
The features of the invention as summarized in the foregoing paragraphs may be employed separately or in various subcombinations in a vehicle leveling system. In a particularly preferred form of the invention, however, the features are combined in a single leveling system providing highly satisfactory construction, operation and/or installation.
Various other features, objects and advantages of the invention will be made apparent from the following description, taken together with the drawings.